[vsnet-alert 25123] MASTER OT J042609.34+354144.8: no outburst yet

Tue Dec 15 18:45:00 JST 2020

This SU UMa type dwarf nova in Perseus is one of my favourite stars. I have
been following it since the discovery in 2012, see [vsnet-alert 14965],
[vsnet-alert 15172] and [vsnet-alert 21676].

ZTF Lasair real-time data: https://lasair.roe.ac.uk/object/ZTF17aabuvss/

Snapshots on Dec. 13 and Dec. 14 definitely show there is no outburst yet.
The star was at quiescence on my Dec. 14 image with the Open University's
COAST instrument on Teide, Tenerife.

MASTER OT J042609.34+354144.8
  20201213.2801  17.01r  ZTF Lasair
  20201214.1339  16.61CV COAST
  20201214.2414  16.35r  ZTF Lasair
  20201215.2391  17.49r  ZTF Lasair

Intervals between the recorded superoutbursts were 340 days in some cases,
sometimes up to 455 days. Here is the light curve from Zwicky Transient
Facility (Masci et al., 2019) Data Release 4:
http://scan.sai.msu.ru/~denis/J0426+3541-ZTF-DR4-LC.gif

It is very likely some outbursts were missed due to conjunction with the
Sun. Variable is in opposition with the Sun on November 30th and not
observable in May-June every year.

Zoomed light curves of two superoutbursts observed by ZTF are showing
different behavior. Please compare
http://scan.sai.msu.ru/~denis/J0426+3541-Aug2018SO.gif and
http://scan.sai.msu.ru/~denis/J0426+3541-Nov2019SO.gif

August 2018 outburst has started with a precursor and peaked at 13.5m
(unless the maximum was missed). November 2019 outburst had no precursor
and reached 13.1m. It is very important to analyze the interval between the
superoutbursts with and without precursor and to compare their peak
brightness. In the case of MASTER OT J042609.34+354144.8, the number of
normal outbursts between the super ones also seems to be changing.

Today's MJD is 59198. It's 392 days since Nov. 2019 superoutburst and 847
days since Aug. 2018 one. The next outburst can start anytime from now
within the following two months. Nightly monitoring is strongly encouraged.

Denis Denisenko